4K TVs

4K TV, also known as ultra-high-definition TV (ultra HD), is the next generation of television picture quality, displaying four times the detail of HD.

Price

4K TVs cost well over $3,000, but prices should fall soon.

Pros

Super-sharp picture quality and the latest TV technology.

Cons

Early 4K TVs are expensive, and our tests show they're not all they're cracked up to be.

Should I buy a 4K TV?

If you want the very latest TV technology and you've got deep pockets, these fancy new 4K TVs might be of interest. If you're not convinced, though, head to our HD TV reviews.

What's so special about 4K TV?

4K, or ultra-high-definition TV (UHD), is the next evolution in television picture quality. Watching 4K TV at its best, you'll see everything on screen in crystal-clear clarity and super-sharp detail.

A 4K TV picture is 3,840 x 2,160 pixels, more than 8 million pixels in total, which is four times the number in Full HD (1,920 x 1,080). It is so detailed that the picture almost feels 3D - and you won't need special glasses to watch it.

The first 4K TVs are available to buy now from the big brands, including Samsung, Panasonic, LG and Sony. There are no 4K TV channels to watch, but the TVs can take standard and high-definition TV, as well as Blu-ray films, and boost them to near 4K picture quality, but are they worth your money?

4K vs HD TV: which should you buy?

We've viewed 4K on professional displays used by filmmakers, so we know how it should look. We've tested 55-inch and 65-inch models from all the major brands in 2013 and, as you can see from our results table, only the Panasonic TV on test achieved near that level overall. At well over £5,000, it's hardly what you'd call cheap.

As well as testing picture and sound quality, we also made side-by-side comparisons between the 4K TVs and our top scoring 55-inch HD TV of 2013 - and we feel the latter is a better-value choice as a premium TV at this stage.

While HD TVs are unable to reach the higher 4K picture quality, we didn't see a sufficient difference on the 4K sets when showing content you might actually watch - such as SD and HD TV, or Blu-ray films - to justify them costing so much more at present.

The 4K future is still a way off

We believe that 4K is the future of television viewing. It makes everything you watch look sharper and more detailed, and you won't need to change the way you already enjoy television as with 3D. However, there are big challenges ahead in getting 4K into your home:

Internet streaming: Currently, a one-hour, compressed 4K film is around 160GB, and it would take you seven and a half hours to download it on 50Mbps broadband.

Blu-ray: Standard dual-layer Blu-rays contain 50GB of space, which is nowhere near enough for a 4K movie, so the content has to be heavily compressed to fit on one disc.

TV channels: Launching a 4K TV channel is possible, but as it costs around five times more than launching an HD channel, broadcasters may worry that not enough people can watch it yet.

We expect 4K TVs to come down in price over the coming years and, as the audience for 4K grows, it will become more viable and cost effective to get 4K content onto your screen.

New technology is coming that can compresse the huge 4K files into forms that can be more easily distributed on TV, Blu-ray or over the internet. MPEG-4 (H.264) video compression helped HD go mainstream, now it is hoped that the next-generation HEVC (H.265) will do the same for 4K.

It took HD TV over a decade to become a bestseller after the first sets launched in 1998. While the current speed of change in the TV industry means 4K may not take so long, we'd still advise you to wait until prices come down and content becomes more widely available before considering the upgrade.

How we tested 4K

We used six experts to assess the picture and sound quality of 4K TVs side-by-side in our lab. Testing material included 4K footage commissioned by Which?, and shot on a cinema-standard camera. This was then played on the TVs using a specialist Redray streaming player, which is as close to true 4K as you can currently get.

We also ran picture quality tests using Blu-ray movies, and standard and high-definition television to see how the TVs were able to 'upscale' the content to near 4K picture quality. As this is a one-off test under unique conditions, the star ratings should not be compared with our non-4K TV reviews.